２４ Quantum Field Theory

２４−１ What is Quantum Field?
○Space is quantum fields, particle is the excited quantum field.
※Vacuum (nothing condition) is the quantum fields where the energy is the lowest.
○In quantum field theory, we consider particles（Material fields）as harmonic oscillators and quantize them.
※The motion of an object that is connected to a spring and vibrates is called "harmonic oscillation".

※Image of Quantum field [1]

○Quantum field theory combines special relativity theory and quantum mechanics.
※Quantum mechanics is an approximate form of quantum field theory limited to the low energy state.
○Prior to the emergence of string theory, the theory describing the smallest scale was quantum field theory.

※ Gauge theory(3 + 1 dimension) is the theory underlying the Standard Model.
※As a method to describe gravity, there is a method based on Newton's theory of gravity and general relativity.

２）Material field and material particles
※Under the "quarks and leptons" definition, the elementary and composite particles made of the quarks (in purple) and leptons (in green) would be matter—while the gauge bosons (in red) would not be matter. However, interaction energy inherent to composite particles (for example, gluons involved in neutrons and protons) contribute to the mass of ordinary matter. [2]